"A Doctor and His Nurse" joke
A doctor and his nurse were having an affair when she announced that she was pregnant. Fearful of his wife finding out, he gave her a large sum of money and ask her to go to Germany to wait out the pregnancy and have the child there.
"If I do that, how will you know when the baby is born?" she asked him.
"After the baby is born, send me a postcard and write 'sauerkraut' on the back, I'll understand what it means," he told her. She agreed and off to Germany she went.
Seven months later, the wife's doctor phoned him to say that he had received a strange postcard in the mail. "I have no idea what it means, dear," she said. He thanked her for letting him know and said he would read it when he got home.
When the doctor arrived home that evening, he read his postcard, "'Sauerkraut', 'Sauerkraut', 'Sauerkraut' - Two with weiners, one without!"
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